[clang] [sema] Improve -Wsign-compare (PR #65684)

[Shafik Yaghmour via cfe-commits]

================
@@ -15423,29 +15489,29 @@ static void AnalyzeImplicitConversions(
     // FIXME: Use a more uniform representation for this.
     for (auto *SE : POE->semantics())
       if (auto *OVE = dyn_cast<OpaqueValueExpr>(SE))
-        WorkList.push_back({OVE->getSourceExpr(), CC, IsListInit});
+        WorkList.push_back({OVE->getSourceExpr(), CC, IsListInit, false});
----------------
shafik wrote:

```suggestion
        WorkList.push_back({OVE->getSourceExpr(), CC, IsListInit, /*IsTopLevelExpr=*/false});
```

https://github.com/llvm/llvm-project/pull/65684